1. Field of the Invention
The invention relates to a control system for refrigerated transport containers.
2. Discussion of the Prior Art
Vehicle mounted refrigerated transport containers are widely used for the transport of perishable goods. Where the container is incorporated in a rigid vehicle an associated refrigeration plant is generally mounted above the vehicle cab. In the case of articulated vehicles, which generally haul removable refrigeration containers, a refrigeration plant is usually mounted at the front end of each individual refrigeration container furthest away from the container doors. In both types of vehicle the refrigeration plants are generally started and controlled locally. Control and monitoring to ensure proper operation requires the driver/operator to have direct access to the refrigeration plant. With rigid vehicles this often necessitates climbing up above the vehicle cab in order to operate the refrigeration plant. As will be appreciated this is somewhat inconvenient and dangerous, as an operator may lose his footing. In both types of vehicle the operator has to stop the vehicle and leave the cab in order to check the operation of the refrigeration plant. This is inconvenient and time consuming and may also be very uncomfortable in bad weather conditions. To ensure proper operation, monitoring of the refrigeration plant needs to be carried out regularly. This may easily be overlooked or deferred due to the inconvenience involved, or if the driver does not have time to stopxe2x80x94for example if the driver has to meet a ferry departure time at a shipping port. This can lead to refrigeration breakdowns or ineffective operation of the refrigeration unit which results in a costly loss of goods which are either destroyed or of unacceptable quality when they reach a delivery destination. There is also a considerable negative environmental impact associated with disposal of the damaged goods.
The present invention is directed towards overcoming these problems.
According to the invention there is provided a control system for a refrigerated transport container of the type comprising a self contained refrigeration plant connected to an associated enclosed refrigeration compartment within the container and operable to regulate the temperature within the compartment, the control system comprising:
sensing means for mounting on the refrigerated transport container for sensing at least one critical operating parameter of the refrigerated transport container,
said sensing means being connected to a radio signal generating means for generating a radio frequency signal corresponding to said sensed parameter condition,
said ratio signal generating means being connected to a short range radio transmitter for transmitting said measured parameter radio signal together with an associated refrigerated transport container identity code radio signal,
a remote operator panel having a radio receiver with means for reception of a radio signal incorporating the refrigerated transport container identity code,
the remote operators panel having a display means for indicating a fault condition of said measured parameter, said remote operator panel radio receiver being connected to the display means for fault indication,
the remote operator panel having means for generating an operating signal to control operation of the refrigeration plant with a view to correcting any abnormal operating condition sensed by said sensing means, said operating signal generating means being connected to a radio signal generating means for generating a radio frequency signal corresponding to said operating signal,
said radio signal generating means being connected to a short range radio transmitter for transmitting said radio signal together with the associated refrigerated transport container identity code radio signal,
a radio receiver for mounting on the refrigerated transport container having means for reception of a radio signal incorporating said refrigerated transport container identity code, and
said radio receiver being connected to a refrigeration plant controller which is operable in response to reception of an operating signal to control operation of the refrigeration plant.
In a particularly preferred embodiment, said remote operator panel is a portable hand-held unit.
In a preferred embodiment the short range radio transmitters are operable to transmit radio frequency signals at 433 megahertz.
In a further embodiment refrigeration plant controller is connected in parallel to the normal operating controls of the refrigeration plant to allow either remote operation or local operation of the refrigeration plant.
In another embodiment the remote operator panel has a visual display for visual indication of the parameter measured by the sensor.
In another embodiment the remote operator panel has alarm means for generating an audible alarm in response to a sensed fault in the measured refrigerated transport container operating parameter.
In a further embodiment the remote operator panel has means for switching the refrigeration plant on or off.
In another embodiment the sensor is at least one temperature sensor mounted within the refrigeration container.
The temperature sensor may incorporate a short-range radio transmitter for wireless transmission of sensed temperature to the refrigeration plant controller or to the remote operator panel.
In a particularly preferred embodiment of the invention the remote operator panel includes an emergency defrost control circuit which allows the normal defrost circuit of the refrigeration unit to be operated at any time necessary during emergency situations. Preferably the emergency defrost control circuit includes re programmable timers, incorporating several electronically controlled parameters to safeguard unwarranted use of the emergency system.
In another aspect the invention provides a monitoring system for a refrigerated transport container of the type comprising a self-contained refrigeration plant connected to an associated enclosed refrigeration compartment within the container and operable to regulate the temperature within the compartment, the monitoring system comprising:
sensing means for mounting on the refrigerated transport container for sensing at least one critical operating parameter of the refrigerated transport container;
said sensing means being connected to a radio signal generating means for generating a radio frequency signal corresponding to said sensed parameter condition;
said radio signal generating means being connected to a short-range radio transmitting for transmitting said measured parameter radio signal, together with an associated refrigerated transport container identity code radio signal;
a remote operator panel having a radio receiver with means for reception of a radio signal incorporating the refrigerated transport identity code;
the remote operator panel having a display means for indicating a fault condition of said measured parameter, said remote operator panel radio receiver being connected to the display means for fault indication.
In a further aspect the invention provides a method for controlling operating conditions in a refrigerated transport container, comprising the steps:
sensing at least one critical operating parameter of the refrigerated transport container;
generating a radio frequency signal corresponding to said sensed parameter condition;
coupling said measured parameter radio signal, together with a refrigerated transport container identity code radio frequency signal both forming a composite radio frequency signal;
transmitting said composite radio frequency signal on a short-range radio transmitter;
on a remote operator panel receiving said composite signal incorporating the said refrigerated transport container identity code on a radio receiver of the remote operator panel;
displaying any measured parameter abnormal operating condition on the remote operator panel;
generating an operating signal to control operation of the refrigeration plant with a view to correcting any abnormal condition;
generating a radio frequency signal corresponding to said operating signal and coupling said radio frequency operating signal with the refrigerated transport container identity code radio frequency signal thus forming a composite radio frequency signal;
transmitting said composite signal on a short-range radio transmitter; and
receiving said composite signal on a radio receiver associated with a refrigeration plant controller for the refrigerated transport container, said operating signal directing the refrigeration plant controller in operating the refrigerating plant.